1. Field of the Invention
The present invention relates to a lift arm for a skid-steer loader.
2. Description of the Related Art
A skid-steer loader is constituted to be steered in a traveling direction by the difference of the number of rotations of both right and left wheels when they are rotated independently, respectively different from a wheel loader. Further, the skid-steer loader is constituted to support a lift arm in a rear portion of a loader main body. With this constitution, the entire length of the skid-steer loader can be shortened while a desired rotation stroke which is necessary to rotate the lift arm is obtained (refer to Japanese Patent Laid-Open Publication No. 6-33476).
Accordingly, the skid-steer loader can be made more compact than the wheel loader and moreover the rotation radius thereof can be shortened. Since the skid-steer loader has these advantages, it is preferably used in civil engineering works such as gardening and the like in a relatively narrow location.
As shown in FIG. 5, in a skid-steer loader 40 disclosed in Japanese Patent Laid-Open Publication No. 6-33476, since the front ends of lift arms 41 are disposed inside of the front wheels, the skid-steer loader 40 is constituted to widen a side field of view. However, since the skid-steer loader 40 is constituted to dispose the front ends of the lift arms 41 inside of the front wheels 47, cylinders 46 for actuating a bucket 42 are disposed below cylinders 43 for actuating the lift arms 41 approximately in parallel therewith. Moreover, connecting arms 44 rotated by the cylinders 46 and connecting rods 45 for transmitting the rotation of the connecting arms 44 to a bucket 42 are disposed forward of the lift arms 41 together.
Accordingly, since the two cylinders 43 and 46 must be disposed on each side of the skid-steer loader 40, the constitution of the skid-steer loader 40 is made complex. Further, cylinders having a long stroke must be used as the cylinders 46.
A lift arm for a skid-steer loader (refer to Japanese Patent Laid-Open Publication No. 2007-254986) and the like are proposed as the constitution in which cylinders for actuating a bucket are disposed to front end sides of lift arms, that is, to a front surface side of the skid-steer loader. Each of the lift arms 50 disclosed in Japanese Patent Laid-Open Publication No. 2007-254986 is divided to two as shown in FIG. 6 so that it is constituted as a first arm portion 51 rotatably supported by a rear portion of a loader main body 55 and a second arm portion 52 constituted downward to the front end side of the first arm portion 51.
The first arm portion 51 is constituted by welding a plurality of sheet metal materials, and the second arm portion 52 is integrally constituted from cast steel. Then, the second arm portion 52 is disposed so as to cover the upper surface of a front wheel 56. Accordingly, the entire length of the skid-steer loader 57 cannot help being made longer than the skid-steer loader 40 disclosed in Japanese Patent Laid-Open Publication No. 6-33476 due to the lift arm 50 constituted so as to cover the front wheel 56.